Water heating and/or space heating appliances use heat created by a burner and transfer this heat to a fluid to be heated. One example of a high efficiency combined water and space heating appliance is described in U.S. Pat. No. 4,541,410 to Jatana. Jatana describes a heating apparatus in which air is mixed with fuel and introduced into a blower which moves the mixture under pressure into the burner in a closed combustion chamber. The combustion chamber is contained within a tank containing water. The products of combustion exit the combustion chamber and pass through a helical tube of several turns within the body of water. The heat of combustion is extracted through the walls of the combustion chamber and the helical exhaust tube. A high efficiency water heater results. The heated water from the water heater is also used to heat the air of a home or building by piping the hot water to a heat exchanger contained within the ducts of the home ventilation system.
The burner in the Jatana device is a cylindrically shaped screen contained within a cylindrical combustion chamber. It has been found that the introduction of the air and fuel mixture into this burner under pressure sometimes results in a swirling circumferential motion leading to noisy operation.
U.S. Pat. No. 4,766,883 to Cameron describes an improvement to Jatana U.S. Pat. No. 4,541,410 which maintains a desired air to fuel ratio regardless of changes in air inlet pressure. The heater uses a venturi type proportioner and an associated fuel regulator to provide an air and fuel mixture of constant ratio which is drawn from the proportioner by a blower and introduced into a closed combustion chamber for efficient burning and heating of a surrounding body of water.
The burner in the Cameron device, like that of the Jatana device, is a cylindrically shaped screen contained within a cylindrical combustion chamber. Contained within the burner screen is a burner divider comprised of three vertical plates radiating from the center of the burner to the surface of the burner screen. The burner divider is as tall as the burner itself and divides the interior volume of the burner into three wedge shaped sectors. In operation, the air and fuel mixture from a blower is forced through a burner distribution plate comprised of a thin sheet of stainless steel having a uniform pattern of holes therein into the interior volume of the burner. The burner distribution plate assures an even distribution of combustion gases. These gases flow upwardly through the sectors of the burner defined by the burner divider. The burner divider prevents the swirling of these combustion gases which might otherwise result in noisy operation but requires the addition of an extra part. This device provides a quietly efficient water and air heater, yet several problems persist.
The burner in the Cameron device exhibits unequal pressures on the burner screen, resulting in "hot spots", areas prone to failure due to carbonization. The Cameron burner also sometimes results in incomplete combustion.
The present invention contemplates a new and improved burner assembly which overcomes the above referred to problems and others and provides a burner of high efficiency, reliability, stability and quality.